Several procedures are known for rendering images containing elements defined as three dimensional data. A known approach to generating images of photo-realistic quality is to consider reflections between all elements simultaneously. The light emission of any given element is considered as being dependent upon the sum of contributions from all other elements and a set of equations is established that represents these interactions. The light emission values for all the elements are then determined simultaneously by solving a system of equations.
This procedure is known as radiosity simulation. The system of equations is usually extremely large, and several refinements to radiosity simulation have been established in order to make implementation of this method practical for scenes containing large numbers of elements.
A known advantage of radiosity is that once the system of equations has been solved, and light emission values determined, the light emission of elements may be considered as view-independent, resulting in a separate radiosity rendering process which is capable of rendering a view from any position. The high efficiency of radiosity rendering makes radiosity particularly suitable for demanding applications, such as generating long sequences of image data frames for film or video, or generating image data in real time.
In the process of radiosity simulation, large data structures are generated which efficiently represent all of the interactions that are necessary in order to obtain light emission values for all of the elements in a scene. In photo-realistic implementation of radiosity simulation, a hierarchical structure of elements is created, such that complex lighting gradients over the surface of various objects may be represented to a high degree of resolution. This necessitates the definition of large numbers of small mesh elements, of which object surfaces are comprised. In order to reduce the amount of memory that is used to represent the resulting system of equations, mesh elements having similar geometry may be associated with a common master element, by way of a transformation function. The use of master elements in hierarchical scene structures has been established for reducing memory requirements within photo-realistic image rendering algorithms such as ray tracing.
Master elements are considered as residing in canonical space, whereas the objects and mesh elements of a three-dimensional scene are considered as residing in world space. The set of transformation functions between master elements in canonical space and elements in world space that is required for ray tracing is known. However, radiosity simulation requires additional functionality to be available, in order to take full advantage of the data structures that are created when mapping mesh elements in world space to master elements.
It is an aim of the present invention to provide an improved method of master element mapping for use in radiosity simulation.